City clinched the title without even playing on Sunday when United, its nearest challenger, surprisingly lost 1-0 at home to last-place West Bromwich Albion.
United had to at least draw to keep the title race mathematically alive but were stunned at Old Trafford when Jay Rodriguez headed home after the break.
Guardiola has won titles with Barcelona and Bayern Munich, while also conquering the Champions League during his Camp Nou reign.
Pep Guardiola's men now hold an unassailable 16-point lead at the top of the table, meaning that with just five games to play nobody can catch the side which has led the league uninterruptedl since the fifth round of fixtures.
He said: "I don't know if I was the first or if I was the second or the third, but I congratulated them face-to-face when I had the chance to do it".More news: Rain, rain go away: OnePlus 6 teased to be waterproof
'No [I won't watch], I have golf game tomorrow, ' he said.
It caps a remarkable Premier League season that has seen City lose just twice thus far and win 28 of their 33 matches with a record-breaking run of 18 successive victories between August and December. Both full-backs will need to be more proactive in their attacking play down the wings.
West Brom now move to within nine points of safety, although they must face Liverpool, Tottenham and fellow relegation battlers Crystal Palace in their final four matches of the campaign.
Former England global Gary Lineker, who now work as a television presenter, tweeted: "Congratulations to @ManCity on winning the Premier League title". At last, Manchester City's players can enjoy a serene Premier League title triumph.
"They won the title because they were the best team, because they won a great amount of points".
"Last season we finished sixth and this season we are going to finish I believe fourth, third or second - hopefully second - and next season we are going to try and improve but let's see what happens".